# Newton's Law of Universal Gravitation

Written by Jerry Ratzlaff on . Posted in Classical Mechanics

All objects in the universe exert a gravitational force of attraction on each other.

## Newton's Law of Universal Gravitation formula

 $$\large{ F_g = G\; \frac{m_1 \;m_2}{r^2} }$$

### Where:

 Units English Metric $$\large{ F_g }$$ = gravitational force $$\large{ \frac{ft}{sec^2} }$$ $$\large{ \frac{m}{s^2} }$$ $$\large{ r }$$ = radius distance between objects $$\large{ ft }$$ $$\large{ m }$$ $$\large{ m_1 }$$ = mass of object 1 $$\large{ lbm }$$ $$\large{ kg }$$ $$\large{ m_2 }$$ = mass of object 2 $$\large{ lbm }$$ $$\large{ kg }$$ $$\large{ G }$$ = universal gravitational constant $$\large{\frac{lbf-ft^2}{lbm^2}}$$ $$\large{\frac{N - m^2}{kg^2}}$$

### Solve for:

 $$\large{ m_1 = \frac{ F_g \; r^2 }{ G \; m_2 } }$$ $$\large{ m_2 = \frac{ F_g \; r^2 }{ G \; m_1 } }$$ $$\large{ r = \sqrt { \frac{G\; m_1 \;m_2}{F_g} } }$$

Tags: Gravity Equations